I am trying to show up the Squareup Payment form in an iframe but it’s showing this error connect.squareupsandbox.com (http://connect.squareupsandbox.com/) refused to connect.
And I think payment form is completely deprecated so what is solution?
That base path URL is still supported and working. Are you using the retired SqPaymentForm that points to the JS library https://js.squareupsandbox.com/v2/paymentform? If so that is retired and no longer supported. You’ll need to use the Web Payments SDK to generate the source_id that’s passed to the Payments API for processing payments. 